A continuing and ongoing trend in the semiconductor field is the ever-increasing density of circuit components in integrated circuits. More and more circuit components are being designed within a given integrated circuit area. Thus, techniques have been developed to substantially reduce the sizes of active devices, metal lines, and intermetal dielectrics, among other components.
With the reduction of circuit component sizes comes a host of problems due to the closer proximity of circuit components. One such problem is cross-talk or electromagnetic interference between adjacent circuit components. For example, a signal present on a metallization line may interfere with another signal present on an adjacent metallization line. Another problem associated with close proximity of circuit components is the potential increased signal delay and reduction in frequency bandwidth. That is, the presence of a grounded metallization layer in proximity to a metallization layer carrying a signal may decrease the signal propagation speed leading to possible delay errors. Also, a close proximity grounded layer may reduce the frequency bandwidth of the signal on an adjacent metallization line. These problems stem from the capacitive coupling between adjacent circuit components, as illustrated in the following example.
FIG. 1 illustrates a cross-sectional view of an exemplary prior art semiconductor device 100 having silicon dioxide (SiO2) material serving as a intermetal layer dielectric (ILD) to separate adjacent electrically-conductive lines. The semiconductor device 100 consists of a silicon substrate 102, a pair of metallization lines 104 and 106, and a silicon dioxide (SiO2) intermetal layer dielectric (ILD) 108. As alluded to, the electromagnetic interference between the adjacent metallization lines 104 and 106 is function of the capacitive coupling between the lines. The capacitive coupling, in turn, is a function of the distance between the adjacent metallization lines 104 and 106 and the relative dielectric constant of the silicon dioxide (SiO2) material 108. Silicon dioxide (SiO2) has a relative dielectric constant of about 4.1.
Accordingly, given a particular dielectric material such as silicon dioxide (SiO2), the trend of decreasing component size to increase circuit density results in more electromagnetic coupling between adjacent components, which may adversely affect circuit performance.